Patent EA-003522-B1 (EA)
Title: Needle retracting mechanism, needle holder and hypodermic syringe
Inventor: SVENDSEN TERJE
IPC: A61M5/32
Filed: 2000-12-18
Abstract: 1. A needle retracting mechanism (1) for a hypodermic syringe (2), comprising a body (3) with a needle retraction chamber (4), which body (3) in a first end (5) is adapted to receive injectant from a syringe barrel (7) and in a second end (6) slidingly supports a needle (27) which by means of a force from a pretensioned actuator (8) is retractable into the needle retraction chamber (4), the actuator (8) being releasable by response to the injectant, characterized in comprising a funnel-shaped entrance opening (18) to the needle retraction chamber (4), a retainer (9) for the actuator (8) and the needle (27), the retainer (9) comprises a compressible portion (10) which in a retaining position is bigger than the entrance opening (18) and abuts funnel-shaped sides (16) of the entrance opening (18), and in a compressed release position is smaller than the entrance opening (18) and can enter the needle retraction chamber (4) together with the needle (27), the pretensioned actuator (8) forces the retainer (9) into the funnel-shaped entrance opening (18), forcing the compressible portion (10) towards the release position, a spacer (11) for keeping the compressible portion (10) in the retaining position, made from a material which after some time in contact with the injectant loses its mechanical strength, whereupon a contact between the spacer (11) and the injectant causes the spacer (11) to lose its mechanical strength, the actuator (8) forces the compressible portion (10) into the release position and into the entrance opening (18), causing the retainer (9) and needle (27) to enter the needle retraction chamber (4). 2. A needle retracting mechanism (1) according to claim 1, characterized in that the compressible portion (10) of the retainer (9) comprises elastic arms (12) which in first ends (13) are integral with a base portion (15) of the retainer (9) and in second ends (14) are moveable between the retaining position and the release position. 3. A needle retracting mechanism (1) according to claim 2, characterized in that the second ends (14) of the elastic arms (12) have oblique end faces (17), corresponding to the funnel-shaped sides (16) of the entrance opening (18). 4. A needle retracting mechanism (1) according to claim 2 or 3, characterized in that the elastic arms (12) have mountings (29) for the spacer (11). 5. A needle retracting mechanism (1) according to any of the claims 2 to 4, characterized by two arms (12) and a spacer (11) formed by a bolt (11), which is mounted between the arms (12). 6. A needle retracting mechanism (I) according to any of the claims 2 to 4, characterized by three arms (12) and a spacer formed by a ring (11'), which is mounted between the arms (12). 7. A needle retracting mechanism (1) according to any of the preceding claims, characterized in that the needle (27) is fixed to the retainer (9). 8. A needle retracting mechanism (1) according to any of the preceding claims, characterized in that the retainer (9) comprises an abutting portion (30) for the actuator (8). 9. A needle retracting mechanism (1) according to any of the preceding claims, characterized in that the spacer (11) is made from alginate. 10. A needle retracting mechanism (1) according to any of the claims 1-8, characterized in that the spacer (11) is made from a water soluble polymer. 11. A needle retracting mechanism according to any of the preceding claims, characterized in comprising an inner sleeve (20) which forms the needle retraction chamber (4) and in an end (21) proximal to the retainer (9) is provided with said funnel-shaped entrance opening (18), the sleeve (20) being movable relative to the body (3), towards the retainer (9), an abutment (35) for the retainer (9) in the second end (6) of the body (3), whereupon a movement of the sleeve (20) towards the retainer (9) causes the funnel-shaped sides (16) of the entrance opening (18) to press the compressible portion (10) of the retainer (9) towards the release position and deform the spacer (11), whereupon the funnel-shaped sides (16) and/or the actuator (8) forces the compressible portion (10) into the release position and into the entrance opening (18), causing the needle (27) to enter the needle retraction chamber (4) by the force of the actuator (8). 12. A needle holder (33) for a hypodermic syringe (2), characterized in comprising a needle retracting mechanism (I) according to any of the claims 1-10, in which the first end (5) of the body (3) is adapted to match an outlet (19) from a syringe barrel (7). 13. A needle holder (33) for a hypodermic syringe (2), characterized in comprising a needle retracting mechanism (1) according to claim 11, in which the end (22) of the sleeve (20) distal to the retainer (9) is adapted to match an outlet (19) from a syringe barrel (7), and the body (3) is slideable on the sleeve (20) from an operating position in which the compressible portion (10) of the retainer (9) is in the retaining position and the needle (27) is operable, to a retracted position in which the sleeve (20) is moved towards the retainer (9), causing the release of the actuator (8) and the retraction of the needle (27). 14. A needle holder (33) according to claim 13, characterized by the sleeve (20) and/or the body (3) having yieldable fixation means (36, 41) for fixing the body (3) in the operating position. 15. A needle holder (33) according to claim 13 or 14, characterized in that the body (3) is slideable on the sleeve (20) from an extended position in which the retainer (9) is located in the first end (5) of the body (3), the actuator (8) is relieved and the needle (27) is drawn into the body (3), to the operating position in which the retainer (9) is located in the second end (6) of the body (3), the actuator (8) is pretensioned and the needle (27) is operable. 16. A needle holder (33) according to claim 15, characterized by the sleeve (20) and/or the body (3) having yieldable fixation means (36, 37) for fixing the body (3) in the extended position. 17. A needle holder (33) according to any of the claims 13-16, characterized in that the sleeve (20) and the body (3) are provided with corresponding ridges (25) and slots (26) for guiding the movement of the body (3) on the sleeve (20). 18. A hypodermic syringe (2') comprising a barrel (7') and a plunger (31'), characterized in comprising a needle retracting mechanism (1') according to any of the claims 1-10, in which the first end (5') of the body (3') forms an extension of the barrel (7'). 19. A hypodermic syringe (2') comprising a barrel (7') and a plunger (31'), characterized in comprising a needle retracting mechanism (1') according to claim 11, in which the first end (5') of the body (3') forms an extension of the barrel (7'), and the end (22') of the sleeve (20') distal to the retainer (9') forms an abutment (32') for the plunger (31') when the plunger (31') is close to the bottom (34') of the barrel (7'), causing a further movement of the plunger (31') into the barrel (7') to force the sleeve (20') towards the retainer (9'), causing the release of the actuator (8') and the retraction of the needle (27').